I've built a Copterx 450 AE V2 and something is causing a lot of vibration. All I see is that the main gear is thrashing all over the place and the rotorhead looks as if it was bent (while running). I put in a HobbyKing main gear I changed the main shaft and rotor head and still there's this vibration, and I still don't know what's causing it.What can I do?

Thx for your response, it turns out that the stock ESC is causing most of my problems I tried it with a 30A ESC and it runs like nobody's business but it's way too small for a 450 heli. What's a good ESC for a 450 size heli?